Conventional lengthy article conveying apparatuses allow the lengthy article to be conveyed between a transfer device and target transfer locations with different heights in a vertical direction with the aid of the transferring activity of the transfer device and a lifting activity of the platform. For instance, the apparatus is comprised of a stacker crane, which is used in an automated storage system, where a pair of storage racks having a plurality of article storages lengthwise and breadthwise for storing articles there and a consign board where the articles are loaded to or unloaded from the outside. The stacker crane performs the article loading work for conveying articles from the origin to the destination, considering the loading board as the target location origin and the storage as the target location destination and the article unloading work for conveying articles from the origin to the destination, considering the storage as the target location origin and the loading board as the target location destination.
A conventional lengthy article conveying apparatus is disclosed in Japanese Patent Preliminary Publication No. 2000-191114, in which a lifted position detecting means is provided for detecting the lifted position of the platform. In this apparatus, a control means for controlling the actuation of the lifting driving means and the transfer device performs the lifting procedure to position the platform at a lifting position for transferring in accordance with information detected by the lifting position detecting means, at which the outside end portion of the platform is received and held by a receiver provided at the target location for the transfer in the article transferring direction. After the lifting procedure has been completed, the control means performs an article transferring procedure by which the transferring device is conveyed in a condition in which the end portion is received and held by the receivers provided at the target location for the transfer (see FIG. 8 of JP 2000-191114).
This patent publication discloses an automated storage system provided with a pair of article storage racks, which are disposed so that the article storing and retrieving directions face one another. In this system, a stacker crane for conveying lengthy articles is provided and is able to freely run along a transfer path formed between the pair of article storage racks. When transferring an article between the stacker crane and the article storage constituting the target location for the transfer, a transfer device is operated to transfer the article under a condition in which the outside end portions of the platform in the article transferring direction are received and held by receivers on the article storage constituting the target location for the transfer and by a receiver on another article storage, an article storage in the other article storage rack facing the article storage constituting the target location for transfer. According to the construction of such a conventional lengthy article transfer apparatus, the load of articles to be conveyed by the transferring device or the load by the weight of the edge side portions of the platform itself acting upon the end portions of the platform can be supported at the target location side for the transfer. Therefore, the platform can be supported in a stable manner by both the cord-like member and the target location for the transfer, and a smooth transfer of articles can be carried out by making the height of articles to be mounted and conveyed with the aid of the transfer device in the platform flush with the height of articles to be supported at the target location for the transfer.
In this conventional lengthy article transfer apparatus, while the transferring process is performed in a condition in which the platform is at the transferring lifting position at which the outer side end portion of the platform in the article transfer direction is received and held by the receiver at the target location for the transfer, the operation of the lifting driving means is maintained in a suspended condition. Therefore, when the transfer procedure of an article from the target location for the transfer to the platform is carried out, as the article is being transferred to the platform side along the article transferring direction, the load acting upon the platform increases and the increase makes the elongation margin of the cord-like member, which suspends and supports the platform, longer, and the lifted position of the platform shifts downwardly in accordance with the elongated margin of the cord-like member. This being the case, if the platform is moved down during the transferring procedure, the platform will be moved down whilst the outside end portions of the platform in the article transfer direction are being received and held at the receiver at the target location for the transfer, thus the platform becomes liable to deformation or damage.
In addition, when the transfer procedure of an article from the platform to the target location for the transfer is carried out, as the article is transferred to the target location for the transfer side along the article transferring direction, the load acting upon the platform decreases and the decrease makes the elongation margin of the cord-like member, which suspends and support the platform, shorter, and the lifted position of the platform is shifted upwardly in accordance with the elongated margin of the cord-like member. This being the case, if the platform is lifted up during the transferring procedure, the outside end portions of the platform in the article transfer direction are borne down by the weight of the article, and just after the rear end portion of the article passes over the outside end portion of the platform in the transferring direction, the rear end portion, which has been born down with the aid of the load of the article, suddenly jerks upward, so that the rear end portion of the article is damaged or the platform is also damaged by the vibration caused by this jerking.